Input/Turbine Speed Sensor Circuit No Signal
The automatic gearbox has its own control unit (TCM), which decides when to shift using speed, temperature, pressure and selector position sensors. The input (or turbine) speed sensor measures how fast the shaft going into the gearbox is turning. Using it and the output sensor, the control unit controls shifts and torque converter lock-up. This code means its signal isn't arriving.
What the car has detected
The control unit is receiving pulses from the output speed sensor but none from the input sensor.
The control unit usually goes into limp mode: on some gearboxes it only allows second gear and reverse after stopping. You can calmly drive to a garage, but don't make long trips like this.
Symptoms
- Engine or gearbox warning light on
- Limp mode: stuck in one gear
- Harsh shifts
- Odd speedometer or displays on some cars
Possible causes
- Failed input speed sensor
- Wiring or connector with breaks or poor connection
- Damage to the toothed part the sensor reads
- Gearbox control unit fault (rare)
Checks for the garage
- With the selector in P or N, compare the input speed in diagnostics with the rev counter
- Check the connector and wiring, flexing them to find intermittent breaks
- Test the sensor per the manual
- Check the toothed wheel if the sensor and wiring are fine
Next step
Have the input speed sensor, its connector and wiring checked, and its reading compared with engine speed.
Go to a garage: the sensor may be inside the gearbox and testing it needs diagnostics.